Water soluble activated polymers are provided containing an active ethyl sulfone moiety having a reactive site located at the second carbon from the sulfone group. In an embodiment, a poly(ethylene glycol) (PEG) derivative is disclosed that is activated with the active ethyl sulfone moiety for selective attachment to thiol moieties on molecules and surfaces. The activated PEG is water soluble, hydrolytically stable for extended periods, and forms hydrolytically stable linkages with thiol moieties. The linkages generally are not reversible in reducing environments. The PEG derivative is useful for modifying the characteristics of substances including modifying biologically active molecules and surfaces for biocompatibility.

This invention relates to active derivatives of poly(ethylene glycol) and related hydrophilic polymers and to methods for their synthesis for use in modifying the characteristics of surfaces and molecules.
Poly(ethylene glycol) (xe2x80x9cPEGxe2x80x9d) has been studied for use in pharmaceuticals, on artificial implants, and in other applications where biocompatibility is of importance. Various derivatives of poly(ethylene glycol) (xe2x80x9cPEG derivativesxe2x80x9d) have been proposed that have an active moiety for permitting PEG to be attached to pharmaceuticals and implants and to molecules and surfaces generally to modify the physical or chemical characteristics of the molecule or surface.
For example, PEG derivatives have been proposed for coupling PEG to surfaces to control wetting, static buildup, and attachment of other types of molecules to the surface, including proteins or protein residues. More specifically, PEG derivatives have been proposed for attachment to the surfaces of plastic contact lenses to reduce the buildup of proteins and clouding of vision. PEG derivatives have been proposed for attachment to artificial blood vessels to reduce protein buildup and the danger of blockage. PEG derivatives have been proposed for immobilizing proteins on a surface, as in enzymatic catalysis of chemical reactions.
In still further examples, PEG derivatives have been proposed for attachment to molecules, including proteins, for protecting the molecule from chemical attack, to limit adverse side effects of the molecule, or to increase the size of the molecule, thereby potentially to render useful substances that have some medicinal benefit, but are otherwise not useful or are even harmful to a living organism. Small molecules that normally would be excreted through the kidneys are maintained in the blood stream if their size is increased by attaching a biocompatible PEG derivative. Proteins and other substances that create an immune response when injected can be hidden to some degree from the immune system by coupling of a PEG molecule to the protein.
PEG derivatives have also been proposed for affinity partitioning of, for example, enzymes from a cellular mass. In affinity partitioning, the PEG derivative includes a functional group for reversible coupling to an enzyme that is contained within a cellular mass. The PEG and enzyme conjugate is separated from the cellular mass and then the enzyme is separated from the PEG derivative, if desired.
Coupling of PEG derivatives to proteins illustrates some of the problems that have been encountered in attaching PEG to surfaces and molecules. For many surfaces and molecules, the number of sites available for coupling reactions with a PEG derivative is somewhat limited. For example, proteins typically have a limited number and distinct type of reactive sites available for coupling. Even more problematic, some of the reactive sites may be responsible for the protein""s biological activity, as when an enzyme catalyzes certain chemical reactions. A PEG derivative that attached to a sufficient number of such sites could adversely affect the activity of the protein.
Reactive sites that form the loci for attachment of PEG derivatives to proteins are dictated by the protein""s structure. Proteins, including enzymes, are built of various sequences of alpha-amino acids, which have the general structure H2Nxe2x80x94CHRxe2x80x94COOH. The alpha amino moiety (H2Nxe2x80x94) of one amino acid joins to the carboxyl moiety (xe2x80x94COOH) of an adjacent amino acid to form amide linkages, which can be represented as xe2x80x94(NHxe2x80x94CHRxe2x80x94CO)nxe2x80x94, where n can be hundreds or thousands. The fragment represented by R can contain reactive sites for protein biological activity and for attachment of PEG derivatives.
For example, in lysine, which is an amino acid forming part of the backbone of most proteins, an xe2x80x94NH2 moiety is present in the epsilon position as well as in the alpha position. The epsilon xe2x80x94NH2 is free for reaction under conditions of basic pH. Much of the art has been directed to developing PEG derivatives for attachment to the epsilon xe2x80x94NH2 moiety of the lysine fraction of a protein. These PEG derivatives all have in common that the lysine amino acid fraction of the protein typically is inactivated, which can be a drawback where lysine is important to protein activity.
Zalipsky U.S. Pat. No. 5,122,614 discloses that PEG molecules activated with an oxycarbonyl-N-dicarboximide functional group can be attached under aqueous, basic conditions by a urethane linkage to the amine group of a polypeptide. Activated PEG-N-succinimide carbonate is said to form stable, hydrolysis-resistant urethane linkages with amine groups. The amine group is shown to be more reactive at basic pHs of from about 8.0 to 9.5, and reactivity falls off sharply at lower pH. However, hydrolysis of the uncoupled PEG derivative also increases sharply at pH""s of 8.0 to 9.5. Zalipsky avoids the problem of an increase in the rate of reaction of the uncoupled PEG derivative with water by using an excess of PEG derivative to bind to the protein surface. By using an excess, sufficient reactive epsilon amino sites are bound with PEG to modify the protein before the PEG derivative has an opportunity to become hydrolyzed and unreactive.
Zalipsky""s method is adequate for attachment of the lysine fraction of a protein to a PEG derivative at one active site on the PEG derivative. However, if the rate of hydrolysis of the PEG derivative is substantial, then it can be problematic to provide attachment at more than one active site on the PEG molecule, since a simple excess does not slow the rate of hydrolysis.
For example, a linear PEG with active sites at each end will attach to a protein at one end, but, if the rate of hydrolysis is significant, will react with water at the other end to become capped with a relatively nonreactive hydroxyl moiety, represented structurally as xe2x80x94OH, rather than forming a xe2x80x9cdumbbellxe2x80x9d molecular structure with attached proteins or other desirable groups on each end. A similar problem arises if it is desired to couple a molecule to a surface by a PEG linking agent because the PEG is first attached to the surface or couples to the molecule, and the opposite end of the PEG derivative must remain active for a subsequent reaction. If hydrolysis is a problem, then the opposite end typically becomes inactivated.
Also disclosed in Zalipsky U.S. Pat. No. 5,122,614 are several other PEG derivatives from prior patents. PEG-succinoyl-N-hydroxysuccinimide ester is said to form ester linkages that have limited stability in aqueous media, thus indicating an undesirable short half-life for this derivative. PEG-cyanuric chloride is said to exhibit an undesirable toxicity and to be non-specific for reaction with particular functional groups on a protein. The PEG-cyanuric chloride derivative may therefore have undesirable side effects and may reduce protein activity because it attaches to a number of different types of amino acids at various reactive sites. PEG-phenylcarbonate is said to produce toxic hydrophobic phenol residues that have affinity for proteins. PEG activated with carbonyldiimidazole is said to be too slow in reacting with protein functional groups, requiring long reaction times to obtain sufficient modification of the protein.
Still other PEG derivatives have been proposed for attachment to functional groups on amino acids other than the epsilon xe2x80x94NH2 of lysine. Histidine contains a reactive imino moiety, represented structurally as xe2x80x94N(H)xe2x80x94, but many derivatives that react with epsilon xe2x80x94NH2 also react with xe2x80x94N(H)xe2x80x94. Cysteine contains a reactive thiol moiety, represented structurally as xe2x80x94SH, but the PEG derivative maleimide that is reactive with this moiety is subject to hydrolysis.
As can be seen from the small sampling above, considerable effort has gone into developing various PEG derivatives for attachment to, in particular, the xe2x80x94NH2 moiety on the lysine amino acid fraction of various proteins. Many of these derivatives have proven problematic in their synthesis and use. Some form unstable linkages with the protein that are subject to hydrolysis and therefore do not last very long in aqueous environments, such as in the blood stream. Some form more stable linkages, but are subject to hydrolysis before the linkage is formed, which means that the reactive group on the PEG derivative may be inactivated before the protein can be attached. Some are somewhat toxic and are therefore less suitable for use in vivo. Some are too slow to react to be practically useful. Some result in a loss of protein activity by attaching to sites responsible for the protein""s activity. Some are not specific in the sites to which they will attach, which can also result in a loss of desirable activity and in a lack of reproducibility of results.
The invention provides water soluble and hydrolytically stable derivatives of poly(ethylene glycol) (xe2x80x9cPEGxe2x80x9d) polymers and related hydrophilic polymers having one or more active sulfone moieties. These polymer derivatives with active sulfone moieties are highly selective for coupling with thiol moieties instead of amino moieties on molecules and on surfaces, especially at pHs of about 9 or less. The sulfone moiety, the linkage between the polymer and the sulfone moiety, and the linkage between the thiol moiety and the sulfone moiety are not generally reversible in reducing environments and are stable against hydrolysis for extended periods in aqueous environments at pHs of about 11 or less. Consequently, the physical and chemical characteristics of a wide variety of substances can be modified under demanding aqueous conditions with the active sulfone polymer derivatives.
For example, conditions for modification of biologically active substances can be optimized to preserve a high degree of biological activity. Pharmaceuticals from aspirin to penicillin can be usefully modified by attachment of active sulfone polymer derivatives if these pharmaceuticals are modified to contain thiol moieties. Large proteins containing cysteine units, which have active thiol moieties, can also be usefully modified. Techniques of recombinant DNA technology (xe2x80x9cgenetic engineeringxe2x80x9d) can be used to introduce cysteine groups into desired places in a protein. These cysteines can be coupled to active sulfone polymer derivatives to provide hydrolytically stable linkages on a variety of proteins that do not normally contain cysteine units.
Specific sulfone moieties for the activated polymers of the invention are those having at least two carbon atoms joined to the sulfone group xe2x80x94SO2xe2x80x94 with a reactive site for thiol specific coupling reactions on the second carbon from the sulfone group.
More specifically, the active sulfone moieties comprise vinyl sulfone, the active ethyl sulfones, including the haloethyl sulfones, and the thiol-specific active derivatives of these sulfones. The vinyl sulfone moiety can be represented structurally as xe2x80x94SO2xe2x80x94CHxe2x95x90CH2; the active ethyl sulfone moiety can be represented structurally as xe2x80x94SO2xe2x80x94CH2xe2x80x94CH2Z, where Z can be halogen or some other leaving group capable of substitution by thiol to form the sulfone and thiol linkage xe2x80x94SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94Sxe2x80x94W, where W represents a biologically active molecule, a surface, or some other substance. The derivatives of the vinyl and ethyl sulfones can include other substituents, so long as the water solubility and the thiol-specific reactivity of the reactive site on the second carbon are maintained.
The invention includes hydrolytically stable conjugates of substances having thiol moieties with polymer derivatives having active sulfone moieties. For example, a water soluble sulfone-activated PEG polymer can be coupled to a biologically active molecule at a reactive thiol site. The linkage by which the PEG and the biologically active molecule are coupled includes a sulfone moiety coupled to a thiol moiety and has the structure PEG-SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94Sxe2x80x94W, where W represents the biologically active molecule, whether the sulfone moiety prior to coupling of the PEG was vinyl sulfone or an active ethyl sulfone.
The invention also includes biomaterials comprising a surface having one or more reactive thiol sites and one or more of the water soluble sulfone-activated polymers of the invention coupled to the surface by a sulfone and thiol linkage. Biomaterials and other substances can also be coupled to the sulfone activated polymer derivatives through a linkage other than the sulfone and thiol linkage, such as a conventional amino linkage, to leave a more hydrolytically stable activating group, the sulfone moiety, available for subsequent reactions.
The invention includes a method of synthesizing the activated polymers of the invention. A sulfur containing moiety is bonded directly to a carbon atom of the polymer and then converted to the active sulfone moiety. Alternatively, the sulfone moiety can be prepared by attaching a linking agent that has the sulfone moiety at one terminus to a conventional activated polymer so that the resulting polymer has the sulfone moiety at its terminus.
More specifically, a water soluble polymer having at least one active hydroxyl moiety undergoes a reaction to produce a substituted polymer having a more reactive moiety thereon. The resulting substituted polymer undergoes a reaction to substitute for the more reactive moiety a sulfur-containing moiety having at least two carbon atoms where the sulfur in the sulfur-containing moiety is bonded directly to a carbon atom of the polymer. The sulfur-containing moiety then undergoes reactions to oxidize sulfur, xe2x80x94Sxe2x80x94, to sulfone, xe2x80x94SO2xe2x80x94, and to provide a sufficiently reactive site on the second carbon atom of the sulfone containing moiety for formation of linkages with thiol containing moieties.
Still more specifically, the method of synthesizing the activated polymers of the invention comprises reacting poly(ethylene glycol) with a hydroxyl activating compound to form an ester or with a halogen containing derivative to form a halogen substituted PEG. The resulting activated PEG is then reacted with mercaptoethanol to substitute the mercaptoethanol radical for the ester moiety or the halide. The sulfur in the mercaptoethanol moiety is oxidized to sulfone. The ethanol sulfone is activated by either activating the hydroxyl moiety or substituting the hydroxyl moiety with a more active moiety such as halogen. The active ethyl sulfone of PEG can then be converted to vinyl sulfone, if desired, by cleaving the activated hydroxyl or other active moiety and introducing the carbon-carbon double bond adjacent the sulfone group xe2x80x94SO2xe2x80x94.
The invention also includes a method for preparing a conjugate of a substance with a polymer derivative that has an active sulfone moiety. The method includes the step of forming a linkage between the polymer derivative and the substance, which linkage can be between the sulfone moiety and a thiol moiety.
Thus the invention provides activated polymers that are specific in reactivity, stable in water, stable in reducing environments, and that form more stable linkages with surfaces and molecules, including biologically active molecules, than previously has been achieved. The activated polymer can be used to modify the characteristics of surfaces and molecules where biocompatibility is of importance. Because the activated polymer is stable under aqueous conditions and forms stable linkages with thiol moieties, the most favorable reaction conditions can be selected for preserving activity of biologically active substances and for optimizing the rate of reaction for polymer coupling.
The synthetic route used to prepare active sulfones of poly(ethylene glycol) and related polymers comprises at least four steps in which sulfur is bound to a polymer molecule and then converted through a series of reactions to an active sulfone functional group. The starting PEG polymer molecule has at least one hydroxyl moiety, xe2x80x94OH, that is available to participate in chemical reactions and is considered to be an xe2x80x9cactivexe2x80x9d hydroxyl moiety. The PEG molecule can have multiple active hydroxyl moieties available for chemical reaction, as is explained below. These active hydroxyl moieties are in fact relatively nonreactive, and the first step in the synthesis is to prepare a PEG having a more reactive moiety.
A more reactive moiety typically will be created by one of two routes, hydroxyl activation or substitution. Other methods are available as should be apparent to the skilled artisan, but hydroxyl activation and substitution are the two most often used. In hydroxyl activation, the hydrogen atom xe2x80x94H on the hydroxyl moiety xe2x80x94OH is replaced with a more active group. Typically, an acid or an acid derivative such as an acid halide is reacted with the PEG to form a reactive ester in which the PEG and the acid moiety are linked through the ester linkage. The acid moiety generally is more reactive than the hydroxyl moiety. Typical esters are the sulfonate, carboxylate, and phosphate esters.
Sulfonyl acid halides that are suitable for use in practicing the invention include methanesulfonyl chloride and p-toluenesulfonyl chloride. Methanesulfonyl chloride is represented structurally as CH3SO2Cl and is also known as mesyl chloride. Methanesulfonyl esters are sometimes referred to as mesylates. Para-toluenesulfonyl chloride is represented structurally as H3CC6H4SO2Cl and is also known as tosyl chloride. Toluenesulfonyl esters are sometimes referred to as tosylates.
In a substitution reaction, the entire xe2x80x94OH group on the PEG is substituted by a more reactive moiety, typically a halide. For example, thionyl chloride, represented structurally as SOCl2, can be reacted with PEG to form a more reactive chlorine substituted PEG. Substitution of the hydroxyl moiety by another moiety is sometimes referred to in the art as hydroxyl activation. The term xe2x80x9chydroxyl activationxe2x80x9d should be interpreted herein to mean substitution as well as esterification and other methods of hydroxyl activation.
The terms xe2x80x9cgroup,xe2x80x9d xe2x80x9cfunctional group,xe2x80x9d xe2x80x9cmoiety,xe2x80x9d xe2x80x9cactive moiety,xe2x80x9d xe2x80x9creactive site,xe2x80x9d and xe2x80x9cradicalxe2x80x9d are somewhat synonymous in the chemical arts and are used in the art and herein to refer to distinct, definable portions or units of a molecule and to units that perform some function or activity and are reactive with other molecules or portions of molecules. In this sense a protein or a protein residue can be considered a molecule or as a functional group or moiety when coupled to a polymer.
The term xe2x80x9cPEGxe2x80x9d is used in the art and herein to describe any of several condensation polymers of ethylene glycol having the general formula represented by the structure H(OCH2CH2)nOH, which can also be represented as HOxe2x80x94CH2CH2xe2x80x94(OCH2CH2)nxe2x80x94OH. PEG is also known as polyoxyethylene, polyethylene oxide, polyglycol, and polyether glycol. PEG can be prepared as copolymers of ethylene oxide and many other monomers.
Poly(ethylene glycol) is used in biological applications because it has properties that are highly desirable and is generally approved for biological or biotechnical applications. PEG typically is clear, colorless, odorless, soluble in water, stable to heat, inert to many chemical agents, does not hydrolyze or deteriorate, and is nontoxic. Poly(ethylene glycol) is considered to be biocompatible, which is to say that PEG is capable of coexistence with living tissues or organisms without causing harm. More specifically, PEG is not immunogenic, which is to say that PEG does not tend to produce an immune response in the body. When attached to a moiety having some desirable function in the body, the PEG tends to mask the moiety and can reduce or eliminate any immune response so that an organism can tolerate the presence of the moiety. Accordingly, the sulfone-activated PEGs of the invention should be substantially non-toxic and should not tend substantially to produce an immune response or cause clotting or other undesirable effects.
The second step in the synthesis is to link sulfur directly to a carbon atom in the polymer and in a form that can be converted to an ethyl sulfone or ethyl sulfone derivative having similar reactive properties. xe2x80x9cEthylxe2x80x9d refers to a moiety having an identifiable group of two carbon atoms joined together. The active sulfone PEG derivative requires that the second carbon atom in the chain away from the sulfone group provide a reactive site for linkages of thiol moieties with the sulfone. This result can be achieved by reacting the active moiety produced in the first step mentioned above, which typically will be the ester or halide substituted PEG, in a substitution reaction with an alcohol that also contains a reactive thiol moiety attached to an ethyl group, a thioethanol moiety. The thiol moiety is oxidized to sulfone and the second carbon away from the sulfone on the ethyl group is converted to a reactive site.
Compounds containing thiol moieties, xe2x80x94SH, are organic compounds that resemble alcohols, which contain the hydroxyl moiety xe2x80x94OH, except that in thiols, the oxygen of at least one hydroxyl moiety is replaced by sulfur. The activating moiety on the PEG derivative from the first reaction, which typically is either halide or the acid moiety of an ester, is cleaved from the polymer and is replaced by the alcohol radical of the thioethanol compound. The sulfur in the thiol moiety of the alcohol is linked directly to a carbon on the polymer.
The alcohol should be one that provides a thioethanol moiety for attachment directly to the carbon of the polymer chain, or that can easily be converted to a thioethanol moiety or substituted moiety of similar reactive properties. An example of such an alcohol is mercaptoethanol, which is represented structurally as HSCH2CH2OH and is sometimes also called thioethanol.
In the third step of the synthesis, an oxidizing agent is used to convert the sulfur that is attached to the carbon to the sulfone group, xe2x80x94SO2. There are many such oxidizing agents, including hydrogen peroxide and sodium perborate. A catalyst, such as tungstic acid, can be useful. However, the sulfone that is formed is not in a form active for thiol-selective reactions and it is necessary to remove the relatively unreactive hydroxyl moiety of the alcohol that was added in the substitution reaction of the second step.
In the fourth step, the hydroxyl moiety of the alcohol that was added in the second step is converted to a more reactive form, either through activation of the hydroxyl group or through substitution of the hydroxyl group with a more reactive group, similar to the first step in the reaction sequence. Substitution typically is with halide to form a haloethyl sulfone or a derivative thereof having a reactive site on the second carbon removed from the sulfone moiety. Typically, the second carbon on the ethyl group will be activated by a chloride or bromide halogen. Hydroxyl activation should provide a site of similar reactivity, such as the sulfonate ester. Suitable reactants are the acids, acid halides, and others previously mentioned in connection with the first step in the reaction, especially thionyl chloride for substitution of the hydroxyl group with the chlorine atom.
The resulting polymeric activated ethyl sulfone is stable, isolatable, and suitable for thiol-selective coupling reactions. As shown in the examples, PEG chloroethyl sulfone is stable in water at a pH of about 7 or less, but nevertheless can be used to advantage for thiol-selective coupling reactions at conditions of basic pH up to at least about pH 9.
In the thiol coupling reaction, it is possible that the thiol moiety displaces chloride, as in the following reaction:
PEG-SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94Cl+Wxe2x80x94Sxe2x80x94Hxe2x86x92PEG-SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94Sxe2x80x94W,
where W represents the moiety to which the thiol moiety SH is linked and can be a biologically active molecule, a surface, or some other substance. However, and while not wishing to be bound by theory, it is believed, based on the observable reaction kinetics as shown in Example 3, that the chloroethyl and other activated ethyl sulfones and reactive derivatives are converted to PEG vinyl sulfone, and that it is the PEG vinyl sulfone or derivative thereof that is actually linked to the thiol moiety. Nevertheless, the resulting sulfone and thiol linkage is not distinguishable, whether from active PEG ethyl sulfone or from PEG vinyl sulfone, and so the active ethyl sulfone can be used at pHs above 7 for linking to thiol groups.
PEG vinyl sulfone is also stable and isolatable and can form thiol-selective, hydrolytically stable linkages, typically in much less time than the haloethyl sulfone or other activated ethyl sulfone, as explained further below.
In a fifth step that can be added to the synthesis, the activated ethyl sulfone is reacted with any of a variety of bases, such as sodium hydroxide or triethylamine, to form PEG vinyl sulfone or one of its active derivatives for use in thiol-selective coupling reactions.
As shown in the examples below, especially Example 3, PEG vinyl sulfone reacts quickly with thiol moieties and is stable against hydrolysis in water of pH less than about 11 for at least several days. The reaction can be represented as follows:
PEG-SO2xe2x80x94CHxe2x95x90CH2+Wxe2x80x94Sxe2x80x94Hxe2x86x92PEG-SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94Sxe2x80x94W.
The thiol moiety is said to add xe2x80x9cacross the double bond.xe2x80x9d The Wxe2x80x94S moiety adds to the terminal CH2 of the double bond, which is the second carbon from the sulfone group SO2. The hydrogen H adds to the CH of the double bond. However, at a pH of above about 9, selectivity of the sulfone moiety for thiol is diminished and the sulfone moiety becomes somewhat more reactive with amino groups.
Alternatively to the above synthesis, the sulfone-activated PEG derivatives can be prepared by attaching a linking agent having a sulfone moiety to a PEG activated with a different functional group. For example, an amino activated PEG, PEG-NH2, is reacted under favorable conditions of pH of about 9 or less with a small molecule that has a succinimidyl active ester moiety NHSxe2x80x94O2Cxe2x80x94 at one terminus and a sulfone moiety, vinyl sulfone xe2x80x94SO2xe2x80x94CHxe2x95x90CH2, at the other terminus. The amino activated PEG forms a stable linkage with the succinimidyl ester. The resulting PEG is activated with the vinyl sulfone moiety at the terminus and is hydrolytically stable. The reaction and the resulting vinyl sulfone activated PEG are represented structurally as follows:
PEG-NH2+NHSxe2x80x94O2Cxe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94CHxe2x95x90CH2xe2x86x92PEG-NHxe2x80x94OCxe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94CHxe2x95x90CH2.
A similar activated PEG could be achieved by reacting an amine-activated PEG such as succinimidyl active ester PEG, PEG-CO2xe2x80x94NHS, with a small molecule that has an amine moiety at one terminus and a vinyl sulfone moiety at the other terminus. The succinimidyl ester forms a stable linkage with the amine moiety as follows:
PEG-CO2xe2x80x94NHS+NH2xe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94CHxe2x95x90CH2xe2x86x92PEG-COxe2x80x94NHxe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94CHxe2x95x90CH2.
The active PEG sulfones of the invention can be of any molecular weight and can be linear or branched with hundreds of arms. The PEG can be substituted or unsubstituted so long as at least one reactive site is available for substitution with the sulfone moieties. PEG typically has average molecular weights of from 200 to 100,000 and its biological properties can vary with molecular weight and depending on the degree of branching and substitution, so not all of these derivatives may be useful for biological or biotechnical applications. For most biological and biotechnical applications, substantially linear, straight-chain PEG vinyl sulfone or bis vinyl sulfone or activated ethyl sulfone will be used, substantially unsubstituted except for the vinyl sulfone or ethyl sulfone moieties and, where desired, other additional functional groups. For many biological and biotechnical applications, the substituents would typically be unreactive groups such as hydrogen Hxe2x80x94 and methyl CH3xe2x80x94(xe2x80x9cm-PEGxe2x80x9d)).
The PEG can have more than one vinyl sulfone or precursor moiety attached or the PEG can be capped on one end with a relatively nonreactive moiety such as the methyl radical, xe2x80x94CH3. The capped form can be useful, for example, if it is desirable simply to attach the polymer chains at various thiol sites along a protein chain. Attachment of PEG molecules to a biologically active molecule such as a protein or other pharmaceutical or to a surface is sometimes referred to as xe2x80x9cPEGylation.xe2x80x9d
A linear PEG with active hydroxyls at each end can be activated at each end with vinyl sulfone or its precursor or derivatives of similar reactivity to become bifunctional. The bifunctional structure, PEG bis vinyl sulfone, for example, is sometimes referred to as a dumbbell structure and can be used, for example, as a linker or spacer to attach a biologically active molecule to a surface or to attach more than one such biologically active molecule to the PEG molecule. The stability of the sulfone moiety against hydrolysis makes it particularly useful for bifunctional or heterobifunctional applications.
Another application for PEG vinyl sulfone and its precursor is dendritic activated PEG in which multiple arms of PEG are attached to a central core structure. Dendritic PEG structures can be highly branched and are commonly known as xe2x80x9cstarxe2x80x9d molecules. Star molecules are generally described in Merrill U.S. Pat. No. 5,171,264, the contents of which are incorporated herein by reference. The sulfone moieties can be used to provide an active, functional group on the end of the PEG chain extending from the core and as a linker for joining a functional group to the star molecule arms.
PEG vinyl sulfone and its precursors and derivatives can be used for attachment directly to surfaces and molecules having a thiol moiety. However, more typically a heterobifunctional PEG derivative having a sulfone moiety on one terminus and a different functional moiety on the opposite terminus group will be attached by the different moiety to a surface or molecule. When substituted with one of the other active moieties, the heterobifunctional PEG dumbbell structure can be used, for example, to carry a protein or other biologically active molecule by sulfone linkages on one end and by another linkage on the other end, such as an amine linkage, to produce a molecule having two different activities. A heterobifunctional PEG having a sulfone moiety on one end and an amine specific moiety on the other end could be attached to both cysteine and lysine fractions of proteins. A stable amine linkage can be achieved and then the hydrolytically stable unreacted sulfone moiety is available for subsequent thiol-specific reactions as desired.
Other active groups for heterobifunctional sulfone-activated PEGs can be selected from among a wide variety of compounds. For biological and biotechnical applications, the substituents would typically be selected from reactive moieties typically used in PEG chemistry to activate PEG such as the aldehydes, trifluoroethylsulfonate, which is also sometimes called tresylate, n-hydroxylsuccinimide ester, cyanuric chloride, cyanuric fluoride, acyl azide, succinate, the p-diazo benzyl group, the 3-(p-diazophenyloxy)-2-hydroxy propyloxy group, and others.
Examples of active moieties other than sulfone are shown in Davis et al. U.S. Pat. No. 4,179,337; Lee et al. U.S. Pat. Nos. 4,296,097 and 4,430,260; Iwasaki et al. 4,670,417; Katre et al. U.S. Pat. Nos. 4,766,106; 4,917,888; and 4,931,544; Nakagawa et al. U.S. Pat. No. 4,791,192; Nitecki et al. U.S. Pat. Nos. 4,902,502 and 5,089,261; Saifer U.S. Pat. No. 5,080,891; Zalipsky U.S. Pat. No. 5,122,614; Shadle et al. U.S. Pat. No. 5,153,265; Rhee et al. U.S. Pat. No. 5,162,430; European Patent Application Publication No. 0 247 860; and PCT International Application Nos. U.S. Ser. No. 86/01252; GB89/01261; GB89/01262; GB89/01263; U.S. Ser. No. 90/03252; U.S. Ser. No. 90/06843; U.S. Ser. No. 91/06103; U.S. Ser. No. 92/00432; and U.S. Ser. No. 92/02047, the contents of which are incorporated herein by reference.
It should be apparent to the skilled artisan that the dumbbell structures discussed above could be used to carry a wide variety of substituents and combinations of substituents. Pharmaceuticals such as aspirin, vitamins, penicillin, and others too numerous to mention; polypeptides or proteins and protein fragments of various functionalities and molecular weights; cells of various types; surfaces for biomaterials, almost any substance could be modified. As used herein, the term xe2x80x9cproteinxe2x80x9d should be understood to include peptides and polypeptides, which are polymers of amino acids. The term xe2x80x9cbiomaterialxe2x80x9d means a material, typically synthetic and sometimes made of plastic, that is suitable for implanting in a living body to repair damaged or diseased parts. An example of a biomaterial is artificial blood vessels.
One straight chain PEG derivative of the invention for biological and biotechnical (applications has the basic structure Rxe2x80x94CH2CH2xe2x80x94(OCH2CH2)nxe2x80x94Y. The PEG monomer OCH2CH2 preferably is substantially unsubstituted and unbranched along the polymer backbone. The subscript xe2x80x9cnxe2x80x9d can equal from about 5 to 3,000. A more typical range is from about 5 to 2,200, which corresponds to a molecular weight of from about 220 to 100,000. Still more typical is a range of from about 34 to 1,100, which corresponds to a molecular weight range of from about 1,500 to 50,000. Most applications will be accomplished with molecular weights in the neighborhood of 2,000 to 5,000, which corresponds to a value of n of from about 45 to 110.
In the above structure, Y represents xe2x80x94SO2xe2x80x94CHxe2x95x90CH2 or xe2x80x94SO2xe2x80x94CH2xe2x80x94CH2xe2x80x94X where X is a halogen. R represents a group that may be the same or different from Y. R can be HOxe2x80x94, H3COxe2x80x94, CH2xe2x95x90CHxe2x80x94SO2xe2x80x94, Clxe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94, or a polymer activating group other than CH2xe2x95x90CHxe2x80x94SO2, Clxe2x80x94CH2xe2x80x94CH2xe2x80x94SO2xe2x80x94, such as is referred to with respect to the above patents and published patent applications.
The active polymer derivatives are water soluble and hydrolytically stable and produce water soluble and hydrolytically stable linkages with thiol groups. The derivatives are considered infinitely soluble in water or as approaching infinite solubility and can enable otherwise insoluble molecules to pass into solution when conjugated with the derivative.
Hydrolytic stability of the derivatives means that the linkage between the polymer and the sulfone moiety is stable in water and that the vinyl sulfone moiety does not react with water at a pH of less than about 11 for an extended period of time of at least several days, and potentially indefinitely, as shown in Example 3 below. The activated ethyl sulfone can be converted to the vinyl sulfone at conditions of basic pH, with the same resulting stability. Hydrolytic stability of the thiol linkage means that conjugates of the activated polymer and a substance having a thiol moiety are stable at the sulfone-thiol linkage for an extended period of time in aqueous environments at a pH of below about 11. Most proteins could be expected to lose their activity at a caustic pH of 11 or higher, so it should be apparent to the skilled artisan that many applications for the active sulfone PEG derivatives will be at pHs of less than 11, regardless of the stability of the sulfone moiety at higher pH.
To be useful for modification of proteins and other substances, it is only necessary that the sulfone be stable for a period of time sufficient to permit the sulfone to react with a reactive thiol moiety on the protein or other substance. The rate of reaction of the sulfone moiety with thiol can vary with pH, as shown in Example 2 below, from about 2 minutes to 30 minutes, which is much faster than the rate of hydrolysis, if any. Vinyl sulfone could be expected to react with thiol over a much broader range of reaction times since it is stable for long periods of time. Also, as shown in Example 3 below, at conditions of basic pH chloroethyl sulfone is not hydrolyzed, but is converted to vinyl sulfone, which remains stable for several days and is even more reactive toward thiol groups. Accordingly, for the purpose of modifying the characteristics of substances, the active ethyl sulfones can also be considered to be hydrolytically stable for an extended period of time over a broad pH range.
Other water soluble polymers than PEG are believed to be suitable for similar modification and activation with an active sulfone moiety. These other polymers include poly(vinyl alcohol) (xe2x80x9cPVAxe2x80x9d); other poly(alkylene oxides) such as poly(propylene glycol) (xe2x80x9cPPGxe2x80x9d) and the like; and poly(oxyethylated polyols) such as poly(oxyethylated glycerol), poly(oxyethylated sorbitol), and poly(oxyethylated glucose), and the like. The polymers can be homopolymers or random or block copolymers and terpolymers based on the monomers of the above polymers, straight chain or branched, or substituted or unsubstituted similar to PEG, but having at least one active site available for reaction to form the sulfone moiety.
The following Example 1 shows the synthesis, isolation, and characterization of poly(ethylene glycol) chloroethyl sulfone followed by the preparation of poly(ethylene glycol) vinyl sulfone from the chloroethyl sulfone. Preparation of other polymeric sulfones having a reactive site on the second carbon from the sulfone group is similar and the steps for doing so should be apparent to the skilled artisan based on Example 1 below and the polymers listed above.

Water soluble activated polymers containing an active ethyl sulfone moiety for modification of surfaces and molecules


A method of treating estrogenic deficiencies in women while further avoiding the appearance of osteoporosis, withdrawal bleeding and cardiovascular diseases in post-menopausal women without any androgenic effect, and no deleterious effects on blood vessels comprising continuously without interruption administering to said women, a combination of 0.5 to 3 mg of an estrogenic compound and 1.5 to 3.75 mg of nomegestrol acetate.

The present invention relates to the field of therapeutic chemistry and more particularly to the field of hormonal pharmaceutical techniques.
A more precise subject of the invention is new pharmaceutical compositions formed by an estroprogestative combination with a view to the correction of estrogenic deficiencies in natural or artificial menopauses or in order to stop ovulation in women during their period of ovarian activity.
In particular a subject of the invention is an estroprogestative combination, characterized in that it is constituted by unit doses containing the combination of a progestative and an estrogen, the two components being present simultaneously in each medicinal dose.
This combination is intended to be administered by oral route.
As is known, the life expectancy of women has passed in less than a century from 50 to 80 years, whilst the average age for the onset of the menopause has remained unchanged. Therefore, women spend a third of their life in a state of estrogenic deficiency which is the origin of the increase in risk of osteoporosis and cardiovascular illnesses. Sequential replacement treatment for the menopause cures the climateric symptomology and prevents osteoporosis and the onset of illnesses. It creates artificial cycles which are followed by a withdrawal bleeding. This therapeutic schema quite particularly suits women for whom the menopause is recent but it is not always well accepted in the long term, which in part explains the poorer observance of treatment (DRAPIER FAURE E.; Gynxc3xa8cologie. 1992, 43: 271-280).
In order to overcome this drawback, combined combinations have been perfected where the two components are taken simultaneously, the progestative having the effect of permanently opposing the proliferative action of the estrogen on the endometrium, by creating an atrophy of the endometrium and as a consequence, the absence of withdrawal bleeding (HARGROVE J. T., MAXSON W. S., WENTZ A. C., BURNETT L. S., Obstet Gynecol, 1989, 73: 606-612).
This xe2x80x9cno periodsxe2x80x9d schema more particularly suits women for whom the menopause is already well in the past. It can be prescribed in courses of sequential combinations in order to improve the long-term observance of replacement hormone treatment for the menopause.
The dose of progestative to be used in a combined replacement treatment is in general deduced from that which is usually prescribed in sequential schemata. In the latter the dose chosen is that which gives over the long term less than 1% endometrial hyperplasia when the progestative is administered discontinuously, more than 10 days per cycle, in post-menopasual women under replacement estrogenotherapy (WHITEHEAD et al., J. reprod. Med, 1982, 27: 539-548, PATERSON et al, Br Med J, Mar. 22, 1980, 822-824).
In the combined treatment, these same progestatives were used at half the dose judged to be effective during a sequential treatment: this is the example of the micronized progesterone, didrogesterone (FOX H., BAAK J., VAN DE WEIJER P., AL-AZZAWI E., PATERSON M., JOHNSON A., MICHELL G., BARLOW D., FRANCIS R., 7th International Congress on the Menopause, Stockholm, Jun. 20-24, 1993, abstr 119) and medroxyprogesterone acetate (BOCANERA R, BEN J., COFONE M., GUINLE I., MAILAND D., SOSA M., POUDES G., ROBERTI A., BISO T., EZPELETA D., PUCHE R., TOZZINI R., 7th International Congress on the Menopause, Stockholm, Jun. 20-24, 1993, abstr 40) which were used at doses of 100, 10 and 5 mg/day respectively, with encouraging results on the clinical and endometrial level. Among the progestatives, nomegestrol acetate appeared to be one of the most effective. Nomegestrol acetate is a non-androgenic progestative derived from 19-nor progesterone, its use in sequential administration during the menopause at the dose of 5 mg/day, 12 days per cycle, in combination with different types of estrogens, allows endometrial hyperplasia to be prevented as shown by a multicentre study on 150 women for one year (THOMAS J. L., BERNARD A. M., DENIS C., 7th International Congress on the Menopause, Stckholm, Jun. 20-24, 1993, abstr 372).
The absence of hyperplasia was confirmed in a study where the nomegestrol acetate was administered at the same dose, 14 days per cycle, in women treated with percutaneous estradiol (BERNARD A. M. et al. Comparative evaluation of two percutaneous estradiol gels in combination with nomegestrol acetate in hormone replacement therapy. XIV World Congress of Gynecology and Obstetrics, FIGO, Montreal, Sep. 24-30, 1994).
The combined treatment is more often used in a continuous fashion, i.e. without interruption. However some people are in favour of using it in an intermittent fashion, for example 25 days per month (BLRKAUSER M. ET AL; Substitution hormonale: une indication bien posxc3xa8e et des schxc3xa8mas de traitement individuels sont dxc3xa8terminants pour le succxc3xa8s du traitement, Mxc3xa8d. et Hyg., 1995, 53: 1770-1773). The aim of the therapeutic interruption is to remove the inhibition exercised by the progestative on the synthesis of the estradiol and progesterone receptors and in this way to avoid the lowering of receptivity of the hormono-dependant tissues.
The progesterone used according to the present invention is nomegestrol acetate which is active by oral route. The estrogen used is free or esterified estradiol, or conjugated equine estrogens which are presented according to a formulation which is active by oral route and in particular estradiol valerate. Nomegestrol acetate and free or esterified estradiol or conjugated equine estrogens are administered in one of the forms which permit administration by oral route: gelatine capsules, capsules, pills, sachets of powder, tablets, coated tablets, sugar-coated tablets etc.
The present invention is characterized in that it is constituted by a new estroprogestative combination, which is active by oral route and administered in a combined manner. A subject of the present invention is also its use in the correction of estrogenic deficiencies, in the prevention of osteoporosis and cardiovascular illnesses in post-menopausal women, or in stopping ovulation in women during their period of ovarian activity.
The compositions according to the invention based on nomegestrol and free or esterified or equine conjugated estrogens are administered in a continuous fashion or intermittent fashion from 21 to 25 days per month.
According to a particular implementation of the invention the compositions contain a quantity of nomegestrol acetate ranging form 1.5 to 3.75 mg and a quantity of free or esterified estradiol or conjugated estrogens ranging from 0.5 to 3 mg. Preferably, the optimal formulations contain 2.5 mg of nomegestrol acetate combined with: either 1.5 mg of free estradiol or 2 mg of estradiol ester or 0.625 mg of conjugated equine estrogens, per daily dose.
This combined administration method can have several therapeutic indications. In post-menopausal women, the estroprogestative combination is intended to compensate for the functional disorders brought about by hypoestrogenism of the menopause, while maintaining an atrophy of the endometrium and avoiding in a majority of them the appearance of withdrawal bleeding.
In women during the period of ovarian activity, young or in the years preceding the menopause, the cyclic administration of the hormonal combination is capable of stopping ovulation and of exercising a contraceptive effect insofar as it has been proved that nomegestrol is capable of stopping the ovulation peak of LH and FSH, starting from 1.25 mg/day (BAZIN B. et al, Effect of nomegestrol acetate, a new 19-norprogesterone derivative on pituitary ovarian function in women. Br. J. Obstet. Gynaecol., 1987, 94: 1199-1204). When the hormonal combination is given for a contraceptive purpose, the aim of nomegestrol acetate is to stop ovulation and for the estrogenic compound to compensate for hypoestrogenia and ensure a better control of the cycle.
A subject of the present invention is also a process for obtaining new pharmaceutical compositions.
The obtaining process according to the invention consists of mixing the active ingredients: nomegestrol acetate and free or esterified estradiol or conjugated equine estrogens with one or more pharmaceutically acceptable, non-toxic, inert excipients.
Among the excipients which can be mentioned are binding and solubilizing agents, compression agents, disintegration agents and slip agents. This mixture can be subjected to direct compression or to several stages of compression in order to form tablets which, if desired, can have their surface protected by a film, by lacquering or coating. The production of tablets by direct compression allows a maximum reduction in the proportion of diluting agents, binding agents, disintegration agents and slip agents. The production of gelatine capsules can be carried out by mixing the active ingredients with an inert diluant and a slip agent. The tablets contain, in particular, mass diluting agents such as lactose, sorbitol for direct compression, marketed under the name NEOSORB 60, Palatinite which is a registered trademark for designating an equimolar mixture of the isomer of -D-glucopyranosido 1,6-mannitol and -D-glucopyranosido 1,6-glucitol crystallized with two molecules of water, mannitol, sorbitol or the mixture lactose/PVP sold under the name Ludipress. The compression binding agents are in general microcrystalline celluloses such as those sold under the name AVICEL PH 101 or AVICEL PH 102. The polyvinylpyrrolidone plays an important role and facilitates the agglomeration of the powders and the compressibility of the mass. To this end polyvinylpyrrolidones are used with a molecular weight comprised between 10000 and 30000 such as Povidone, Kollidon of a grade comprised between 12 and 30. The mixture also contains slip or anti-electrostatic agents so that the powder does not agglomerate in the feed hoppers. In this respect, colloidal silicas can be mentioned which are sold under the name AEROSIL 100 or AEROSIL 200. The mixture also contains disintegration agents which allow disintegration or crumbling which conforms to pharmaceutical standards. There can be mentioned as useful disintegration agents, polymers of cross-linked vinylpyrrolidones such as those sold under the names Polyplasdone or Polyclar AT, carboxymethylamidons such as those sold under the names Amigel or Explotab, cross-linked carboxymnethylcelluloses or croscarmelloses such as the compound sold under the name AC-DI-SOL greater than  In addition, the preparation contains lubrication agents which facilitate the compression and ejection of the tablet from the tablet compressing machine. There can be mentioned as lubrication agents, glycerol palmitostearate sold under the name Precirol, magnesium stearate, stearic acid or talc. After compression the tablets can be coated in order to ensure their storage or to facilitate their deglutination. The coating agents are either of cellulose origin such as cellulose phthalate (Sepifilm, Pharmacoat), or of polyvinyl origin of Sepifilm ECL type, or of saccharose origin such as the sugar for sugar-coating of Sepisperse DR, AS, AP OR K (coloured) type. The tablets, whether coated or not, can in addition, be surface or bulk coloured, by plant or synthetic colouring agents (for example chinolin yellow lacquer or E 104). The proportions of the different constituents varies according to the type of tablet to be produced. The content of active ingredients can vary from 1.5 to 3.75 mg for nomegestrol acetate and from 0.5 to 3 mg for free or esterified estradiol or for conjugated equine estrogens. The dilution agents vary from 20 to 75% of the total mass, the slip agents from 0.1 to 2% of the total mass, the compression binding agents vary from 2 to 20%, the polyvinylpyrrolidone from 0.5 to 15%, the disintegration agents vary from 2 to 5.5% for the cross-linked polyvinylpyrrolidone or the carboxymethylamidon, from 2.0 to 3.0% for the croscarmellose. The quantities of lubricating agents vary as function of the type of agents from 0.1 to 3.0%.
The compositions according to the invention are intended to be administered once per day. However, depending on the therapeutic requirements, administration can be split up (twice per day) or on the other hand, repeated (two tablets per day). The following examples illustrate the invention. They in no way limit it.

Hormonal composition consisting of an oestrogen compound and of a progestational compound


Acidic and basic cleaning compositions using toxicologically-acceptable ingredients for cleaning fruits and vegetables are provided. Clear liquid formulations comprising oleate, alcohol ethoxylates and buffers are sprayed onto apples, lettuce and the like to remove soil and unwanted deposits.

The present invention relates to methods for removing dirt and other unwanted residues from produce, e.g., fruits and vegetables, which is intended for ingestion by humans or lower animals and to detersive compositions, especially in liquid form, which are especially suitable practicing said methods.
It is well-known and appreciated by consumers that fruits and vegetables should be thoroughly washed prior to ingestion in order to remove soils and other unwanted residues which may be undesirably clinging to the surfaces thereof. In addition, some consumers wish to remove the artificial xe2x80x9cwaxyxe2x80x9d coatings which may be applied to some fruits to retard moisture loss for increased storage life and to enhance their appearance. It has been estimated that 95% of consumers recognize the need for thorough washing but, ordinarily, only use tap water for this purpose. On the order of 5% of those consumers who do wash their vegetables use a household cleaner, typically a liquid dishwashing product, to help ensure cleanliness. However, dishwashing products are not specifically intended for such use, inasmuch as they are usually designed to provide high, persistent suds which makes them inconvenient to remove from the fruits or vegetables which have been washed therewith. It will also be appreciated that the formulation of truly effective compositions, especially those which can be used safely by individual consumers, for washing fruits and vegetables presents a unique problem to the formulator, inasmuch as many art-disclosed cleaning ingredients would, presumably, not be desirable for use in direct contact with foods where they might not be fully removed.
Moreover, it would be especially desirable to provide effective, toxicologically-acceptable cleaning compositions for fruits and vegetables in the form of substantially low-sudsing liquid solutions which are clear or which have only minimal haziness. Liquid solutions are convenient for the user, since they can be applied directly to soiled fruits and vegetables, followed by rinsing in tap water. The clarity of the liquids connotes cleanliness to the user and is thus highly desirable. Low sudsing is an important attribute so that removal of the solution by rinsing is achieved quickly and easily. It would also be of advantage if such compositions could be provided in the form of concentrates, which could be diluted by the consumer before use and/or applied to the fruits and vegetables as a direct spray-on.
Unfortunately, many toxicologically-acceptable cleaning ingredients do not meet the aforesaid requirements for clear, low-sudsing, dilutable liquid products. Many detersive surfactants form cloudy or even opaque suspensions in water. Of course, many surfactants are specifically designed to be high sudsing. Still others form relatively intractable phases in their concentrated form.
It has now been discovered that certain nonionic surfactants, properly formulated with oleic acid or water-soluble oleate or laurate salts and other ingredients can provide liquid compositions having the desired properties described above. It has been discovered that preferred compositions can be formulated in the acid pH range and have a desirable clean, xe2x80x9cnon-soapyxe2x80x9d feel to the users"" hands. Alternatively, certain compositions can be formulated in the basic pH range. Even when such basic compositions do have a soapy feel, they are preferred over the acidic compositions herein for removing artificial waxy coatings, especially from fruit such as apples. However, the invention also comprises basic compositions having less soapy feel.
The use and selection of cleaning ingredients for the purpose of washing fruits and vegetables is described by the United States Code of Federal Regulations, Title 21, Section 173.315: xe2x80x9cIngredients for use in washing or lye peeling of fruits and vegetablesxe2x80x9d. These regulations restrict the ingredients that may be used for direct contact with food to those described as xe2x80x9cgenerally regarded as safexe2x80x9d (GRAS), and a few other selected ingredients. These sections also provide certain limitations on the amount of material that can be used in a given context.
Among these ingredients, the experienced formulator will find only a few ingredients which can provide effective cleaning of hydrophobic residues, such as waxes, oils, or man-made chemical residues such as pesticides. It is recognized these types of residues are removed most readily by surface active ingredients in water, or by organic solvents largely in the absence of water. Other types of soils, especially particulate insoluble soils that do not readily disperse in water, are effectively removed by surface active materials in water, especially when aided by complex anionic salts, such as citrates (polycarboxylates), or polyphosphate salts.
Within this limited group of ingredients the range of effective cleaning compositions well suited to the task of cleaning fruits and vegetables, especially as practiced by individual consumers, have not been previously described. It is desirable to formulate liquid compositions which are amenable to either direct application to produce, preferably by spray application, or could be provided in suitable concentrated form to allow convenient dilution in a bowl or sink of water for washing of produce by immersion. Further, it is desirable the compositions are low sudsing, and easily rinsed, without leaving residue. Preferred compositions should be mild to the hands, especially for direct application.
Food Chemical News, Inc., 1991, p. 334.1, reports that PEG 200-9500 has been cleared under xc2xa7178.3750 as a component in articles for use in contact with food (Fed. Register, Oct. 15, 1968). Nonetheless, for washing produce, polyethylene glycol should be affirmed as GRAS.
The present invention encompasses methods for cleaning produce, especially fruits and vegetables, (and compositions, as disclosed hereinafter, for practicing said methods) at either an acidic pH, or basic pH. The present invention comprises several aspects including:
I. A method for cleaning produce comprising contacting the surfaces of said produce by direct application of an aqueous cleaning solution typically comprising:
(a) from about 0.01% to about 15% of C8-C18 fatty acid, and preferably less than about one eighth of the amount of nonionic surfactant in an acidic product;
(b) optionally, except that it is required when the pH is less than about 5.5, from about 0.1% to about 4% by weight of nonionic surfactant, especially ethoxylated/propoxylated adducts of aliphatic C12-18 alcohols;
(c) optionally, from about 0.1% to about 4% by weight of organic polycarboxylic acid, preferably citric acid;
(d) optionally, up to about 0.2% by weight of an acid-stable anionic surfactant such as the alkali or alkaline earth salts of dodecylbenzene sulfonate;
(e) optionally, a toxicologically-acceptable acidic buffer, other than said polycarboxylic acid and/or said fatty acid, sufficient to maintain the desired pH;
(f) optionally, a toxicologically-acceptable basic buffer such as potassium and/or sodium salts of carbonate and/or bicarbonate;
(g) optionally, a toxicologically-acceptable preservative; and
(h) the balance comprising an aqueous carrier selected from water and, optionally, low molecular weight, toxicologically-acceptable organic solvent such as ethanol, glycerol, etc.;
wherein said aqueous solution has a pH either in the range of from about 2.5 to about 5.5, preferably about 4, or in the range of 9.5 or greater, and preferably employs potassium carbonate as buffer (f) to provide a pH of about 11, said composition preferably being essentially free of any material that is not toxicologically acceptable.
I(A) The inventions disclosed herein can preferably encompass a method for cleaning produce, e.g., fruits and vegetables, at an acidic pH comprising contacting the surfaces of said produce by direct application with an aqueous cleaning solution comprising:
(a) from about 0.1% to about 4% by weight of nonionic surfactant, preferably non-nitrogen containing nonionic detergent surfactant, especially ethoxylated/propoxylated adducts of aliphatic C12-18 alcohols;
(b) from about 0.01% to about 0.4% by weight of oleic acid, the ratio of nonionic detergent surfactant to oleic acid being more than about 8:1;
(c) from about 0.1% to about 1.5% by weight of organic, preferably naturally derived, organic polycarboxylic acid, e.g., citric acid;
(d) optionally, a toxicologically-acceptable acidic buffer, especially potassium hydrogen citrate, sufficient to maintain the desired pH;
(e) optionally, up to about 0.2% by weight of an acid-stable anionic surfactant such as the alkali or alkaline earth salts of dodecylbenzene sulfonate;
(f) optionally, a toxicologically-acceptable preservative; and
(g) the balance comprising an aqueous carrier;
wherein said aqueous solution has a pH in the range of from about 2.5 to about 5.5, preferably about 4.
I(B) The inventions disclosed herein can also preferably encompass a method for cleaning fruits and vegetables at a basic pH, comprising contacting the surfaces of said fruits and vegetables with an aqueous cleaning solution comprising:
(a) optionally, from about 0.1% to about 4% by weight of nonionic surfactant, especially ethoxylated/propoxylated adducts of aliphatic C12-18 alcohols;
(b) from about 0.1% to about 15% by weight of a member selected from the group consisting of sodium or potassium oleate (preferred) or from about 0.5% to 10% by weight of sodium or potassium laurate;
(c) optionally, but preferably, from about 0.2% to about 4% by weight of potassium and/or sodium polycarboxylate, having detergent building capability and preferably being derived from natural sources, such as potassium and/or sodium citrate, as a dispersant for particulate soils;
(d) optionally, a toxicologically-acceptable basic buffer such as potassium carbonate; and
(e) the balance comprising an aqueous carrier selected from water and water-ethanol;
wherein said aqueous cleaning solution has a pH of 9.5 or greater, and preferably employs carbonate salt, or salts, as buffer (d) to provide a pH of about 11 to about 12.5.
I(C) The inventions herein can also encompass a more specific method for cleaning fruits and vegetables at a basic pH, preferably more than about 9.5, comprising contacting the surfaces of said fruits and vegetables with an aqueous cleaning solution comprising potassium oleate, preferably at a level of more than about 0.5%. Potassium oleate is mild, rinses well, has minimal odor, is effective in removing unwanted materials, especially wax, from apples, does not oversuds, and is very safe, even when the composition is misused and the vegetable, or fruit, etc., is not completely rinsed. Therefore, it is a uniquely preferred surfactant for use in cleaning food materials like vegetables and fruits. The potassium cation is much more useful than the sodium cation since the potassium oleate is quite soluble whereas the sodium oleate tends to form a less soluble soap, especially at low temperatures.
I(D) Another preferred, concentrated, alkaline method for cleaning produce comprises contacting the surfaces of produce with a cleaning solution containing from about 0.5% to about 15%, preferably from about 0.75% to about 8%, more preferably from about 1% to about 5%, detergent surfactant, preferably one that is GRAS, and more preferably said oleate surfactant said cleaning solution having a pH of from about 8 to about 12.5, preferably from about 9.5 to about 12.3, especially when the detergent surfactant is a soap such as the said oleate, more preferably from about 11 to about 12. Such compositions when used in an effective amount to clean apples coated with wax, will provide effective removal of the wax. Removal of wax from apples is one of the most difficult cleaning tasks and therefore is indicative of overall superior performance.
I(E) Yet another preferred variation in the above methods for cleaning produce involves placing said cleaning solutions in a spray container to provide a spray of said solution to distribute the said solution, or solutions, over the surfaces of the produce while utilizing only a minimum amount of the cleaning solution and minimizing the exposure of the remaining solution to the atmosphere, where the solution is more likely to be contaminated and/or exposed to oxygen, both of which tend to cause undesirable changes in the solutions from aesthetic and/or performance considerations. In such spray processes, there is only need for a relatively small amount of material in the package, and for individual consumer use, this is desirable, since some consumers will not be able to manipulate large weights. For consumer usage, typically, the container will contain no more than about two gallons (about four liters), especially when the container is a spray container, even one that has a tube that permits the spray device to be manipulated while the bulk container remains in place. Preferably such spray containers contain about one liter, or less, of cleaning solution.
II. The invention also encompasses acidic and basic cleaning compositions in both concentrated and dilute forms, especially adapted for practicing said methods. (In the following disclosure, the lower amounts of the specified ingredients denote the dilute forms of the compositions herein and the higher amounts denote the concentrated forms which are typically diluted by a factor of from about 2 to about 3) Such compositions include the following.
II.(A) A composition for cleaning fruits and vegetables at an acidic pH, comprising:
(a) from about 0.1% to about 7.5%, preferably from about 0.3% to about 4.5%, by weight of nonionic surfactant, as described above;
(b) from about 0.01% to about 0.75%, preferably from about 0.1% to about 0.5%, by weight of oleic acid, the ratio of oleic acid to nonionic detergent surfactant being less than about 1:8;
(c) from about 0.1% to about 7.5%, preferably from about 0.3% to about 4.5%, by weight of organic polycarboxylic acid, preferably citric acid;
(d) optionally, a toxicologically-acceptable acidic buffer;
(e) optionally, a toxicologically-acceptable preservative; and
(f) the balance comprising an aqueous carrier;
wherein said composition has a pH in the range of from about 2.5 to about 5.5.
Preferably, the acidic compositions herein contain from about 0.5% to about 3.0% by weight of potassium citrate as the acidic buffer (d) and have a pH of about 4. Optionally, such compositions can contain up to about 1%, preferably about 0.2%, by weight of an acid-stable anionic surfactant, as described above.
II.(B) A composition for cleaning fruits and vegetables at a basic pH, comprising:
(a) optionally, from about 0.1% to about 4%, preferably about 0.3% to about 1.0%, by weight of nonionic surfactant as described above;
(b) from about 0.1% to about 15%, preferably from about 1% to about 5%, by weight of a member selected from the group consisting of sodium or potassium oleate (preferred), sodium or potassium laurate, or mixtures thereof;
(c) from about 0.2% to about 4% by weight of polycarboxylic acid salt, especially potassium hydrogen citrate;
(d) optionally, a toxicologically-acceptable basic buffer; and (e) the balance comprising an aqueous carrier selected from water and water-ethanol;
wherein said composition has a pH of 9.5 or greater.
Preferably, the basic compositions herein contain from about 0.5% to about 1.5% by weight of potassium and/or sodium carbonate buffer and have a pH of about 11.5.
II.(C) Preferred compositions for use herein in a concentrated alkaline method contain from about 0.1% to about 15%, preferably from about 0.5% to about 8%, more preferably from about 1% to about 5%, detergent surfactant, preferably one that is GRAS, and have a pH of from about 8 to about 12.5, preferably from about 9 to about 12.3, more preferably from about 11 to about 12. Such compositions when used in an effective amount to clean apples coated with wax, will provide effective removal of the wax. Removal of wax from apples is one of the most difficult cleaning tasks and therefore is indicative of overall superior performance.
II.(D) The present invention also encompasses detersive compositions with an improved tactile impression which are especially adapted for cleaning fruits and vegetables, comprising:
(a) at least about 0.1%, preferably from about 0.5% to about 8%, most preferably from about 1% to about 5%, by weight, of a C12-C18 fatty acid or salt thereof;
(b) at least about 0.05%, preferably from about 0.1% to about 10%, most preferably from about 0.25% to about 3.0%, by weight, of a water-soluble polyethylene glycol having a molecular weight of about 200, or higher;
(c) a water or water-ethanol fluid carrier, said composition having a basic pH.
The balance of the composition can comprise various optional adjunct materials, pH-adjusting agents, perfumes or essences, preservatives and the like.
In a preferred mode, component (b) has a molecular weight in the range from about 400 to about 9500.
Typical compositions herein are wherein component (a) is potassium oleate, and wherein the weight ratio of (a):(b) is in the range from about 1:2 to about 15:1.
The compositions having improved tactile impression are typically formulated in the basic pH range, preferably from about pH 9.5 to about pH 12.3. Preferred compositions have a viscosity at room temperature of less than about 100 centipoise, preferably less than about 50 centipoise for sprayable compositions.
II.(E) Preferred compositions for use herein contain only materials that are GRAS to protect against possible misuse by the consumer. Traditionally, most suggestions for cleaning of fruits and/or vegetables have contemplated a commercial scale where there is typically more control over the conditions, especially the amount and thoroughness of rinsing. The present invention, especially the methods involving use of hand held trigger activated spray means are primarily/solely suitable for use by individual consumers so that it is essential that extra safety be built into the product. Failure to rinse thoroughly after cleaning is less of a concern if all of the ingredients are GRAS. This is especially important when concentrated basic compositions suitable for removal of wax from apples are used. The larger amounts of materials needed for removal of wax create an heretofore unknown level of risk for the individual consumers, many of whom are not likely to read, or follow, instructions which would permit safe use of non-GRAS materials.
The ingredients in the above compositions are preferably selected and used in proportions which provide substantially clear compositions. Substantially clear includes only minimal haziness, and preferably the compositions are completely clear. The ingredients are also selected to have minimal odor, both initially and after storage. The lack of odor is especially important in compositions for use on food. The compositions preferably have a viscosity that is more than about 10 centipoise, preferably more than about 50 centipoise when at rest, but thin under shear to permit easy dispensing, especially from spray containers.
Below pH about 9.7, the compositions can exhibit some objectionable fatty acid odor. Even at the optimal pH""s above 11, some odor can persist. In order to mask this odor, the compositions can contain a perfume or essence ingredient. Especially preferred for this use are terpenes derived from citrus fruit, e.g., oranges, lemons, limes, grapefruits, tangerines, tangelos, etc,.
All documents cited are incorporated herein by reference.
The following toxicologically-acceptable ingredients are used in the preparation of the preferred compositions herein. By xe2x80x9ctoxicologically-acceptablexe2x80x9d is meant that any residues from the ingredients of the compositions which may remain on the fruits or vegetables cleansed therewith are safe for ingestion by humans and lower animals.
Nonionic Surfactantxe2x80x94The nonionic surfactant is preferably selected from materials known well-known in the art, such as alkylene oxide (ethylene oxide or propylene oxide) adducts of C10-18 aliphatic alcohols or acids, C10-18 aliphatic alcohol adducts of glucose (alkyl polyglucosides). The specific nonionic surfactant selected ideally has a hydrophilic-lipophilic balance (HLB) greater than about 10, and a cloud point above about 35xc2x0 C. in the composition. The United States Code of Federal Regulations (CFR) specifically describes an ethylene oxide/propylene oxide adduct of C12-18 aliphatic alcohol of molecular weight of about 800. Such a material is available as PLURAFAC RA-20 (BASF).
It is to be appreciated that in the acidic compositions herein, the alkoxylated alcohol functions substantially as a cleansing agent, whereas in the basic compositions the alkoxylated alcohol functions mainly as a dispersant for any soap curd which may form during the cleansing operation. Further, it is recognized that the selection of non-nitrogen containing nonionics can minimize the possibility of microbial growth in the dilute surfactant compositions.
Fatty Acid and/or Salts Thereofxe2x80x94The acidic compositions herein are formulated using an unsaturated fatty acid; oleic acid is preferred and convenient for this use. However, the particular oleic acid that is selected should preferably be low in polyunsaturates, e.g., contain less than about 10%, preferably less than about 7%, more preferably less than about 5% and will typically have an Iodine Value (IV) of from about 70 to about 100, preferably from about 83 to about 95, more preferably from about 85 to about 90. Polyunsaturated fatty acids are not preferred herein, due to odor problems. However, this is primarily from aesthetic considerations since such acids are effective in cleaning. The amount of polyunsaturated fatty acids should be less than about 8%, preferably 0%. The amount of polyunsaturated fatty acids with more than about two double bonds should be less than about 1%, preferably 0%. Saturated fatty acids are unacceptable as they have limited solubility for longer chainlength materials (xe2x89xa7C12), or have unacceptable odor (xe2x89xa6C14). For example, stearic and/or tallow fatty acids soaps, even potassium soaps, do not have enough solubility at room temperature, where most produce cleaning is done by individual consumers, to formulate even compositions containing the minimum of about 0. 1% soap required for acceptable cleaning. Other specific solubilizing surfactants in higher proportions would be required to solubilize these saturated fatty acids. Pamolyn 100 FGK oleic acid is a good example of a suitable commercial fatty acid.
For the acidic compositions, other low HLB ( less than 6) nonionics can be substituted, such as monoglycerides, but these are less preferred than oleic acid. The purpose of these materials is to provide acceptable cleaning with low sudsing to the compositions. Preferably, in the acidic compositions the oleic acid is used in an amount that is less than about 1:8 (about 12%) by weight of the nonionic surfactant. For the basic compositions, sodium oleate or sodium laurate can be employed, but only sodium oleate is described as GRAS on the CFR. The fatty acid (or salt thereof) functions both to provide a cleansing action and to dampen sudsing. In the acidic formulation, the pH of very dilute mixtures is kept below 7.0 by citric acid to prevent formation of cloudiness.
Polyethylene Glycolxe2x80x94The water-soluble polyethylene glycol polymer (PEG) employed herein is the known article of commerce and is available under a variety of trade names, of which CARBOWAX (Union Carbide Corporation) is exemplary. PEG""s in the average molecular weight range of from about 200 to about 20,000 can be used herein, and PEG as CARBOWAX in the average molecular weight range of at least about 400, typically 400 to about 9500, is convenient and preferred. As disclosed above, the compositions herein will comprise at least about 0.05%, by weight, of the PEG and will typically comprise from about 0.1% to about 10%, by weight, of PEG. The amounts used can vary with the molecular weight of the PEG, the amount of oleate or other fatty acid used in the composition, the desired viscosity of the composition, and like factors within the discretion of the formulator. The following Table 1 illustrates the variation in viscosity which can be effected using various levels of PEG and varying PEG molecular weights in a liquid composition (Control) comprising 3% potassium oleate. Table 1 also illustrates the effect of sodium benzoate (Bz) on viscosity.
In a typical mode, the preferred compositions herein that have an improved tactile impression will comprise oleate:PEG weight ratios in the range from about 1:2 to about 15:1, preferably from about 1:1 to about 10:1.
Tactile Impressionxe2x80x94The compositions herein which contain the polyethylene glycol are characterized not only by their excellent cleaning performance and sudsing/rinsability properties, but also by their improved viscosity properties and improved xe2x80x9cfeelxe2x80x9d. While, as disclosed above, the improved viscosities of the compositions herein are readily demonstrated quantitatively using standard measurement techniques, the improved feel of the compositions which come into contact with the users"" hands is a qualitative tactile impression. However, this improved, xe2x80x9cnon-slipperyxe2x80x9d, xe2x80x9cnon-soapyxe2x80x9d improvement in skin feel can be demonstrated by rubbing Test (PEG-containing) and Control (no PEG) compositions on the hands or inner forearms of volunteer graders. Even in such rudimentary tests, the graders can readily distinguish the improved tactile impression of the compositions made in accordance with this invention.
Optional Surfactantsxe2x80x94Optionally, acid or base stable anionic surfactants can be employed, as allowed by the United States Code of Federal Regulations, Title 21, Section 173.315. Preferred are salts of dodecylbenzene sulfonate, typically at levels up to 0.2%. Also described in the CFR are phosphate esters of ethylene and/or ethylene/propylene oxide adducts of aliphatic alcohols, dioctyl sulfosuccinate, or 2-ethylhexyl sulfate, typically but these materials suffer from lack of stability at either acid or basic conditions.
Sequestrant/builderxe2x80x94The organic polycarboxylic acid, or salt thereof, e.g., citric acid, is used as a sequestrant/builder in the acidic compositions herein or sodium and/or potassium citrate as used in the basic compositions herein are standard items of commerce. Other organic poly carboxylic acids, especially those that are GRAS, such as tartaric, malic, etc. acids, can also be used. When formulating the basic formulations herein, it is preferred to use the potassium salt, as compared with the sodium salt, to provide ease of formulatability. Complex phosphates can also be used, but are generally avoided due to regulatory considerations.
Bufferxe2x80x94Toxicologically-acceptable acidic or basic buffers can be used in the compositions herein to maintain product pH in the acid or base range. For ease of formulatability, it is highly preferred that such acidic and basic buffers be in their potassium salt form. Citric acid is a preferred acid pH buffer, and in the basic pH systems, potassium citrate is a preferred dispersant for particulate soils. Potassium carbonate is a convenient and preferred basic pH buffer. Sodium bicarbonate is a highly desirable material to add to the compositions of this invention as a part of the buffering system since it is readily available as baking soda in food grade and is therefore relatively inexpensive, while providing a highly desirable purity to the composition. Compositions formulated with a mixture of potassium and sodium cations in molar ratios of from about 1:1 to about 10:1, preferably from about 2:1 to about 8:1, more preferably from about 4:1 to about 5:1 potassium to sodium, e.g., as provided by mixtures of potassium hydroxide (hydrate) and sodium bicarbonate, have desirable Theological properties. The compositions are thick, so as to cling to the fruit or vegetable until spread, but are readily dispensed, e.g, by means of a spray device, either aerosol or finger-activated pump. The levels and identities of the ingredients are adjusted to provide products having the desired viscosities as set forth herein, e.g., more than about 5, preferably more than about 10, more preferably more than about 50 centipoise when at rest, and less than about 150, preferably less than about 100, more preferably less than about 50 centipoise under shear of xe2x89xa7xcx9c1000 secxe2x88x921.
The ability of the preferred compositions containing mixtures of both sodium and potassium cations to shear thin is important to promote easy dispensing, especially when the compositions are sprayed, while maintaining the ability to be thick, cling, and delay run off after being applied to the produce.
The pH is preferably not greater than about 12.5, and especially does not contain large amounts of buffer at higher pHs for consumer safety, especially when the compositions are sprayed.
Preservativexe2x80x94The strategy of formulating the present compositions at either high or low pH is based on the reduced tendency for biological growth of contaminants, such as bacteria, fungi, or molds, at either high pH ( greater than 9) or low pH ( less than 5). At neutral pH, an increased reliance on preservatives is required to insure the lack of biological growth through contamination in making or in use. The acidic compositions herein do preferably contain a minimal amount, typically from about 0.01% to about 0.2% by weight, of a toxicologically-acceptable preservative in order to prevent the growth of fungi, bacteria or like in the product on storage. Standard food-grade preservatives such as potassium sorbate/sorbic acid and/or sodium benzoate/benzoic acid, or mixtures thereof, are suitable for such purposes. For example, from about 0.01% to about 0.2% of benzoic acid or its sodium or potassium salts can be used. In general, the basic pH compositions herein do not require a preservative, although one can be added if desired.
Antioxidants The use of commercial oleic acid, or oleate salts, can be complicated by development of off-odors and/or yellowing of the compositions in which they appear. These undesirable properties are believed to be caused by complex side reactions initiated by the reaction of oxygen with primarily the polyunsaturated components of the fatty acid stock. These results can be avoided, or minimized, by avoiding contact with air, or by controlling the quality of the fatty acid stock so that the amount and type of polyunsaturates are minimized as described above, and/or by the addition of antioxidants.
It has been found, that the addition of tocopherols (e.g., Vitamin E, or tocopherol acetates) in alkaline formulations is advantageous, as they do not degrade, nor do they impart a strong color. They inhibit the development of off-odors for extended periods of time so that the need for masking scents is minimized, or eliminated, particularly for oleic acid stocks of high quality, as described above. The use of butylated phenols, such as BHT and BHA is also useful, but their effectiveness appears more limited and they can impart stronger colors to the compositions. Other food grade antioxidants such as Vitamin C and sulfites, are desirable to prevent deterioration of the compositions by the action of oxygen, but care must be taken since vitamin C can suffer color degradation and sulfites can cause odor problems. Sulfites also have been the target of potential health concerns. In acidic formulations, vitamin C can be advantageous since its color degradation is less severe.
Fluid Carrierxe2x80x94The major proportion (typically, 90%-98%, by weight) of the compositions herein comprises water as the solubilizing carrier for the ingredients. As noted in the Examples hereinafter, water-ethanol can also be employed and is especially preferred when formulating basic pH compositions herein. The ethanol level preferably should not exceed 2% in the solution used to clean the produce, to avoid an alcoholic odor, especially when spraying. Other compatible, water-soluble, low molecular weight solvents such as glycerol can also be used.
It has been discovered that for the acidic compositions (pH 5.5, and below) described herein, a unique non-slippery solution feel is imparted by the low pH compositions, especially at total levels of surfactant plus oleate below about 3%. Such characteristic appears to be unique to these compositions, compared to comparable compositions at neutral or high pH. This solution feel is preferred for ease of handling and easy rinsing.
The compositions herein are preferably used by placing them in a package comprising either an aerosol container or a non-aerosol spray device xe2x80x9cspray means.xe2x80x9d Said spray means is any of the manually activated, preferably xe2x80x9ctrigger-type,xe2x80x9d means for producing a spray of liquid droplets as is known in the art. Typical spray means are disclosed in U.S. Pat. Nos.: 4,082,223, Nozawa, issued Apr. 4, 1978; 4,161,288, McKinney, issued July 17, 1979; 4558,821, Tada et al., issued Dec. 17, 1985; 4,434,917, Saito et al., issued Mar. 6, 1984; and 4,819,835, Tasaki, issued Apr. 11, 1989, all of said patents being incorporated herein by reference. The spray bottle, or container can be any of the ones commonly used for containing hard surface cleaner detergent compositions. Examples of bottles are those in U.S. Design Pat. Nos.: 244,991, Weekman et al., issued July 12, 1977; and 275,078, Wassergord et al., issued Aug. 14, 1984, said patents being incorporated herein by reference.
The spray means herein can also include those that incorporate a propellant gas into the liquid and those that will foam even detergent compositions having a viscosity of less than about 15 cps. The device can also be one that can be adjusted to either give a liquid spray or a foam. The spray means herein are typically those that act upon a discrete amount of the composition itself, typically by means of a piston that displaces the composition and expels the composition through a nozzle to create a spray of thin liquid.
Preferred articles include the compositions herein that are suitable for use in the processes described herein, in a package that can provide a spray. Such articles are not widely marketed. This is surprising in view of the clear advantages for such products for use by individual consumers. The typical use involves treating individual items of produce, which would make preparation of a xe2x80x9cbathxe2x80x9d wasteful.
In a preferred process for using the products described herein, and especially those formulated to be used at full strength, the product is sprayed onto the food product to be cleaned, rubbed, rinsed and/or wiped off with a suitable material like cloth, sponge, a paper towel, etc. Surprisingly, the compositions and processes described herein, especially those that are alkaline, can provide effective disinfectancy.
All parts, percentages, and ratios herein are xe2x80x9cby weightxe2x80x9d unless otherwise stated. All number values are approximate unless otherwise stated.

Cleaning methods and compositions for produce